Seems like the Model 66 is a favorite of many, me included. I also have one, a M66-1. Bought it new in the box at a gun show, it's from 1981. I liked it well enough to make it my EDC, put a set of Altamont stock on it so I could keep the factory ones in nice shape.
My real favorites, though, are my pair of .41 Magnums. A Model 57, "S" prefix, from 1968, and a Model 58 "S" prefix, from 1967. The M58 is another ANIB purchase, spent its whole life in two different safes until I picked it up from the 2nd owner.